This invention is in the field of charging or evacuating valves for hydraulic, pneumatic, or refrigeration systems. A well-known type of such valve is the Schrader valve. Perhaps the best known use of the Schrader valve is an automobile (and other pneumatic) tires; it is also common to home and automobile air conditioning systems. Although the Schrader valve has certain advantages, there are places where it is unacceptable. A typical such place is a system using gaseous helium; another is a system operating at a high temperature; yet another is a system using a fluid incompatible with the rubber seat of a Schrader valve.